The present invention relates generally to the field of power electrical inductors such as used in connection with power electronic and power distribution circuits. More particularly, the invention relates to a novel approach to the design and configuration of inductors to enhance their thermal transfer properties when used in conjunction with conductive or convective cooling apparatus.
In the field of power electronic devices, a wide range of circuitry is known and currently available for converting, producing and applying power to loads. Depending upon the application, such circuitry may convert incoming power from one form to another as needed by the load. In a typical arrangement, for example, constant (or varying) frequency alternating current power (such as from a utility grid or generator) is converted to controlled frequency alternating current power to drive motors, and other loads. In this type of application, the frequency of the output power can be regulated to control the speed of the motor or other device. Many other applications exist, however, for power electronic circuits which can convert alternating current power to direct current power, or vice versa, or that otherwise manipulate, filter, or modify electric signals for powering a load. Circuits of this type generally include inverters, converters, and similar switched circuitry. Other applications include universal power controllers, micro-turbine generators, universal power sources, and so forth.
Many power electronic circuits of the type mentioned above require filtration through the use of chokes or inductors used on either a line side or a load side of the circuitry, or both. Such inductors serve to limit current, shape waveforms and improve harmonics. In addition, certain circuitry may employ direct current link inductors, such as between two inverter circuits in a drive application. Common mode inductors are also employed, depending upon the system requirements.
Depending upon the system configuration, input and output power levels, frequencies, and so forth, chokes and inductors used in power electronic circuits can be quite sizeable. The physical packaging in such applications becomes problematic, both from mounting and interconnection standpoints. Furthermore, due to the inherent functionality of the inductors, large amounts of heat may be generated during operation which must be dissipated to maintain the internal temperatures of the inductor within a desired thermal operating range. In large packaged inductors, such thermal management becomes extremely problematic. For example, currently available inductors that can be scaled to power electronic circuits include packaging configurations in which a bundle of conductive wire is disposed within an encapsulated shell. A potting material, typically epoxy, is disposed within the shell to seal the structure. These structures are not, however, completely modular in design, and require termination of leads extending from the shell. While a certain amount of cooling can be provided against a face of the shell, and cooling conductors can be routed through an aperture formed in the shell, these measures are typically insufficient to develop the desired level of cooling of interior regions of the structure.
There is a need, therefore, for improved inductor assemblies that can be more easily and efficiently cooled during operation. There is a particular need for inductors that can be packaged in a modular manner and cooled by convective and/or conductive cooling media for enhanced power and magnetic densities in packaging that maintain desired temperature ranges.